1. Field of the Invention
The present invention relates to a print controller, drawing controller, data processing method and storage medium.
2. Related Background Art
In a conventional print controller and drawing controller having drawing means that executes drawing according to an input drawing command to a first bitmap image and drawing process specifying means that performs alpha blending specification (transparency degree specification) in executing drawing according to an input object as the drawing command to the first bitmap image, the drawing according to the input drawing command to the first bitmap image has been executed as follows.
A conventional example is shown in FIGS. 1A and 1B. FIG. 1A shows a first bitmap image before drawing is executed according to a relevant drawing command.
The first bitmap image is constituted by a bitmap image of RGB colors each having 8 bits per pixel, and a rectangle of RGB=(255, 0, 0) is drawn therein. A region where nothing is drawn has a value of RGB=(255, 255, 255).
FIG. 1B shows a result of drawing the rectangle of RGB colors=(255, 255, 0) each having 8 bits per pixel with a transparency degree specification of an alpha blending value=(128)=50% for 8 bits per pixel to FIG. 1A.
Since the area 1 has a value of RGB=(255, 0, 0), the area 2 has a value of RGB=(255, 255, 128) and the alpha blending value has a transparency degree specification of 50%, the area 3, which is an overlap of rectangles, has a value of RGB=(255, 128, 0).
Calculation in executing the drawing is performed according to the following equations:ResultR=(α/255)×SrcR+(1−(α/255))×DestR;ResultG=(α/255)×SrcG+(1−(α/255))×DestG; andResultB=(α/255)×SrcB+(1−(α/255))×DestB,where ResultR is a value of the first bitmap image after the drawing is executed, SrcR is a value of color of an input object, DestR is a value of the first bitmap image before the drawing is executed, and α is an alpha blending value of the input object.
However, if drawing means does not support the alpha blending drawing, the conventional print controller and drawing controller having drawing means that executes drawing according to an input drawing command to a first bitmap image and drawing process specifying means that performs alpha blending specification (transparency degree specification) in executing drawing according to an input object as the drawing command to the first bitmap image cannot provide expected results. In addition, if the bit depth of the first bitmap image is less than the bit depth of the alpha blending value, as in case of 1 bit per pixel for each of RGB colors, not 8 bits per pixel for each of RGB colors, expected results cannot be obtained.